Eosinophils and basophils are rare blood cells that play important roles in pulmonary inflammation associated with asthma. We have identified eosinophils in blood using an antibody to VLA4 . VLA4 is an adhesive integrin that is normally expressed only at low levels on neutrophils, the major granulocyte population. We have begun to examine the phenotypic responses of inflammatory cells in response to characteristic inflammatory mediators in blood. We have also begun to define the adhesive properties of eosinophils, using inflammatory mediators that have preferential effects on eosinophils rather than neutrophils. In year 16, we have begun to examine inflammatory cell behavior in normal and asthmatic patients.